Process of producing phosphorus and phosphoric oxides



E. J. FRAN KE Sept. 5, 1933.

PRO'CESS OF PRODUGING PHOSPHORUS AND PHOSPHORIC OXIDES Filed Deo. 19, 1928 2 Sheets-Sheet l Eva/enla?? Fein/ard el-Pranlze Patented Sept. 5, 1933 PATENT OFFICE PROCESS F PRODUCING yPILIOSPHORUS AND PHOSPHORIC OXIDES Edward J. Pranke, Bayside, N. Y., assignor to Grangers Manufacturing Company,

` Mass., a corporation' Boston, of Massachusetts Application vDecember 19, 192s Serial No. 327,055

3 Claims.l

This invention relates to an improved process of producing phosphorus and phosphoric oxides.

According to my invention the vapors of elemental phosphorus formed pass off as such from v the surface of the molten charge, and they are then swept along by the current of gas passing through the furnace. 1 generally prefer that the gas used be neutral to phosphorus so that it will be swept out of my apparatus by such gas in the elemental form, and it may then be recovered as such or treated as desired. I may oxidize it outside of my furnace if 1 nd this is desirable; and my furnace is so constructed that 1 may oxidize it Within the furnace by using an oxidizing gas such as air instead of a gas inert to phosphorus. In any event the product of the reaction taking place on the hearth is elemental phosphorus which, as stated, passes off as vapor from the surface ofthe molten charge.

In the accompanying drawings, forming a part of this specification, in which like numerals designate like parts in all the views:

' Fig. lfis a diagrammatic sectional View of a furnace made in accordance with this invention; and- Fig. 2 is a diagrammatic sectional View of the same made at right angles to the section shown in Fig. 1. f

1 represents any suitable form of furnace pro- 30 vided with a hearth 2 in which can be placed a v charge 3 consisting of an intimate mixture of ground natural phosphates, and carbon, or

ground natural phosphates, carbon and silica, or

natural phosphates and other substances which 5 when heated to a suflicient temperature will evolve phosphorus. 4 is a chamber located beneath the charge 2, and provided at or near the top thereof With a suitable gate5 which can be opened or closed by manipulating the rod 6. 7 is a hopper in which the charge is placed, and 8 is a screw conveyor which moves the charge from the hopper 7 into the chamber 4. During this operation the gate 5 over the top of the chamber 4 is closed so that the material inv the hearth 2 cannot fall down into chamber 4. A piston head 9 on a geared piston rod 10 is operated by the gears 11. During the filling of chamber 4 the piston is in the lowest position. After the chamber 4 has been filled the gate 5 is opened and piston head 9 is moved upward by actuating the gears 11 by any suitable means, forcing the material in the chamber into the space above. By proper control this movement may be made as slow or as fast as may be desired within wide 5 limits. 12 is an electrode in a water-cooled sleeve (Cl. .2S- 165) 13. 14 is a similar electrode, while a third electrode, not shown, may be provided. While I prefer to use S-phase alternating current it is obvious that single-phase or any desired number of phases may be used with a suitable number and arrangement of electrodes to correspond. When B-phase current is used two of the electrodes may be arranged as desired. 15 is a suitable electrode holder connected to one terminal of the power supply. 16 represents any suitable means for 65 controlling the distance of the electrodes from one another. 17 is a suitable arch made of fireresistant brick and 18 yrepresents the molten charge.

19 is a spillway for the molten slag and 2O a 7.0 chamber for catching the slag fiowing over the lip 21, which consists of heat-resistant brick. 22 and 23 are retaining walls, capable of resisting high temperatures. The space between these walls is filled with loose tiles or broken fire-brick 25, constituting a checkerwork heat regenerator.

Openings 26, 27 are provided in the outer wall 23, one being used as an inlet for air or other gas, while the other is used as an exit for the gases which may then be treated for the recovery of the phosphorus or phosphorous compounds. For regenerative purposes the flow of air or other gas is periodically reversed, that is while it enters at the opening 27 the reaction gases pass out at the opening 26. After a period of time the air or other gas is made to enter through the opening 26 and then the gases pass out through the opening 27. Such reversal is periodic.

29 and 30 represent water coolednozzles of a fuel oil, gas, powdered coal or other finely divided fuel injector, by means of which a fiame can be produced, utilizing for the greater part of the air required the hot air from the previously heated checkerwork, thereby utilizing said heat to pro duce an exceedingly hot flame above the slag surface. This flame may be used in conjunction with the electrical heating means already de scribed, or the electrical heating may be used alone Without the fuel heating, or the electrical heating may be used only to assist in starting the furnace into operation, or the electrical equipment may be entirely removed, the openings completely closed, and the furnace heated primarily by means of the fuel nozzles, alternating these in parallel with the flow of gases through the furnace.

If I wish to product phosphorus, Without oxidizing the same in the furnace, I use the electric current as the primary source of heat, and instead of blowing air through the regenerators I use an inert gas, for example, nitrogen, which enables me to utilize a large part of the heat of the gaseous products by means of the regenerators.

I thus have a double-purpose furnace, in which I can produce either elementary phosphorus or phosphoric pentoxide, and in which I may use electrical heating alone, or when making phosphoric pentoxide either electrical heating alone or fuel heating alone, or any combination thereof desired, and in which, when making either product I utilize a large part of the heat of the gaseous products by means of the generators described.

In operating the furnace it is obvious that the rate of feeding the charge to the hearth is completely in the control of the operator. He can hold the charge in the furnace as long a time or as short a time as he may desire or believe necessary to obtain the best results. These results are best obtained by feeding in fresh charge as fast as the phosphorus has been substantially liberated from the reacted material at the surface which will then be removed over slag lip 21. The operator can control the amount of energy put into the furnace either by moving the electrodes farther apart or nearer together, or by applying lower or higher voltages, I-Ie can also obtain a certain amount of control by regulating the admission of air or inert gases through the inlets 26 or 27. In operating the furnace it isY intended that the 110W of gases shall be for a suitable time in one direction and shall then be reversed for a similar time, in which case the functions of openings 26 and 27 are reversed as described above.

It will be readily seen that when air or other gases is forced into the furnace through the opening 27, it passes through the checkerwork 28 and thence over the surface of the molten charge from which phosphorus is being evolved, causing a rapid oxidation of the phosphorus and passing out through the checkerwork 25 and the opening 26. The heat thereby released,`and radiating downwardly tends to further raise the temperature of the molten charge, and radiating upwardly strikes the walls of the arch and is reflected and re-radiated upon the surface of the molten charge, thus making the greatest possible use of the heat of oxidation at the place where it is most useful. This is an advantage which is hardly gained at all in furnaces in which the charge is introduced above the surface of the molten charge. In my furnace, the gaseous .products are carried directly over the surface of the slag which is flowing over the spillway 19, and since the temperature of the gases is exceedingly high at this point the slag is maintained at a very high degree of fluidity, thereby favoring the greatest evolution of gaseous reaction products, while at the same time ensuring free movement of the reacted slag over the slag lip 21 from whence it falls into the slag chamber 20 or any other suitable receiver. The'gases are then passed through the checkerwork 25 which absorbs a large part of the heat thereof. When the checkerwork has reached such a high temperature that it does not readily or efficiently absorb more heat the direction of flow of the gases is reversed, resulting in the incoming gases being heated to a high temperature before reaching the space above the hearth.

On reversal of the direction of flow of the gases through the furnace, air is blown through the opening 26 and the checkerwork 25, and the gaseous products of combustion pass through the checkerwork 28 and out through the opening 27. The slag thereupon reverses its direction of flow and moves over the spillway and slag lip and drops into the slag pit on the left side of the furnace, corresponding respectively to 19, 21 and 20.

It is obvious that those skilled in the art may vary the steps constituting the process, as well as the arrangement of parts constituting the apparatus, Without departing from the spirit of the invention, and therefore, I do not Wish to be limited to the above disclosure except as may be required by the claims.

By the expression excluding air from said zone as used in some claims and the expression with substantial exclusion of air as used inV other of the claims I mean air (oxygen) in excess of that which is normally present at atmospheric pressure in the interstices of the mixture or charge as fed into the reaction zone.

What I claim is: v

1. The process of producing phosphorus oXids which comprises forcing a mixture of ground natural phosphates, silica and carbon, with substantial exclusion of air, up to a highly heated zone where elementary phosphorus and carbon monoxid are liberated, the said Zone being heated by the combustion of the said phosphorus and carbon monoxid and a nely divided fuel above the said zone. f

2. The process of producing phosphorus oxids which comprises forcing a mixtureV of fground natural phosphates, silica and carbon, with substantial exclusion of air, up to a highly heated Zone where elementary phosphorus and carbon monoxid are liberated, the said zone being heated by the combustion, by means of a current of pre-heated air, of the said phosphorus and carbon monoxid and a finely divided fuel above the said zone. Y 3. The process of producing phosphorus oxids which comprises forcing a mixture of ground natural phosphates, silica and carbon, with substantial exclusion of air, up to a highly heated zone where elementary phosphorus and carbon monoxid are liberated, and causing the residual slag from which the phosphorus has been substantially eliminated to flow on the surface of said mixture in said zone and to pass progressively permanently from said'zone, the said zone being heated by the combustion of the said phosphorus and carbon monoxid and a `nely divided fuel above the said Zone.

EDWARD J. PRANKE.V 

